System for and method of connecting a hardware modeling element to a hardware modeling system

ABSTRACT

An improved system for and method of connecting a hardware modeling element to the pin electronics circuitry of a hardware modeling system, with the improved system having circuitry and structures that will allow it to be connected to a hardware modeling system that is powered, circuitry to indicate to the pin electronics circuitry that the improved system is connected to it, circuitry to identify the hardware modeling element supported by the improved system to the hardware modeling system, circuitry to indicate to the hardware modeling system when the hardware modeling element is initialized so evaluation of it by the hardware modeling system can commence, circuitry to generate selectable supply voltages for the powering the hardware modeling element, and a hardware modeling element connector that will allow the connection of a family of hardware modeling elements to the same connector without the need to change the connector.

This is a continuation, division, of application Ser. No. 07/359,624filed May 31, 1989, now abandoned.

FIELD OF THE INVENTION

The present invention relates to adapter systems used to connecthardware modeling elements to the pin electronics circuitry of ahardware modeling system.

BACKGROUND OF THE INVENTION

Hardware modeling systems ("HMS") provide integrated circuit designerswith a tool for making accurate, full function, simulation models ofcomplex devices. These complex devices, often called hardware modelingelements ("HMEs"), serve as their own models. An important, but oftenoverlooked, aspect of the HMSs is the adapter to which the HME isattached that connects the HME to the pin electronics circuitry ("PEL")of the HMS.

The adapter, with a connected HME, of prior HMSs could not be connectedto a PEL that was powered. It has been necessary to shut down the HMSbefore connecting the adapter. This was necessary for a variety ofreasons as set forth below.

If the adapter had an electrostatic charge on it when its signal pinsconnected to the PEL, the discharge of the electrostatic charge to theinternal PEL circuitry could damage the HMS and the HME. Anotherpossible problem is that the signal ground of the PEL and adapter werenot equalized before the pins of the two systems mated. If there werenot equalization, the signal ground of the adapter could be floating,and the power supply voltages could couple through the HME or othercomponents to signal lines, sending a damaging voltage level to the PEL.Still another possible problem is that upon mating of the adapter andPEL, the bulk capacitance on the adapter may cause a large in-rushcurrent that could damage the PEL or adapter, and disrupt the operationof the HMS.

Prior adapters were not configured to support more than one specificpin-out configuration for an HME. If two HME pin-out configurations weredifferent, generally, they could not be connected to the same adapterwithout modification.

Prior adapters did not have an on-board means to provide the HMS withinformation regarding the HME attached to the adapter. Nor were theyreadily alterable to change the configuration of the adapter circuitryto support special HME and HMS needs. Also, importantly, prior adapterswere not configured so that external equipment could be attached forvarious uses with the HMS.

The present invention overcomes these and other problems, as fullydemonstrated in the remainder of the specification and drawings.

SUMMARY OF THE INVENTION

The present invention is an improved system for, and method of,connecting HMEs to an HMS designed to model them. The system of theinvention is embodied as a device adapter circuit board ("DAB"), towhich the HME to be modeled is attached. The DAB, with a connected HME,is attached to the HMS.

The specification will refer to electronic components or circuitry thatmay include a group of components that carry out known functions. Thosecomponents or circuit elements that are known by those skilled in theart will be referred to generally by their common name or function, andwill not be explained in detail.

The DAB includes circuitry, specific electronic components, and severalphysical structures. Each element of the DAB will now be discussed. TheDAB system connector connects the DAB to the PEL of the HMS. The numberof system connectors for a particular DAB depends on the number of HMEsignal pins the DAB supports. Because the system connector is thestructure that connects the DAB to the PEL, most of the other DABcomponents and circuitry connect to the system connector, eitherdirectly or indirectly.

The DAB live insertion circuitry permits the DAB to be connected to, orremoved from, the PEL of a powered HMS. To permit this, the liveinsertion circuitry provides a safe means for dissipating electrostaticcharge, equalizing the signal ground between the DAB and PEL, andgradually powering the DAB and HME to prevent massive current in-rush.

The output of the DAB live insertion circuitry is input to the HMEVCCgeneration circuitry. This circuitry is capable of generating HMEVCCpower supplies at different levels to match the VCC requirements of theHME connected to the DAB.

The output of the HMEVCC generation circuitry is input to a matrix ofpads or grid means, to which the HME to be modeled connects. Thisstructure includes not only the HMEVCC connection pads, but connectionpads for signal ground, and connection pads for the various signal pinsof the HME.

The matrix connection pads intended for connecting to the various HMEsignal pins are referred to as the HME footprint. The HME footprint isdesigned to support a number of pin-out configurations, such as a classor family of HMEs.

The HME footprint pads connect to the system connector through aconfiguration area. The lines that connect the HME footprint pads to thesystem connector pins come to the surface of the DAB at this area. Thisallows the DAB circuitry to be configured differently, for instance tocut and reconnect the signal lines, by the user, to accommodate specialneeds of the HME or HMS.

The DAB circuitry preferably includes a non-volatile memory device. Thedevice, when directed, provides the PEL and HME with informationregarding the characteristics of the HME connected to the DAB and of theDAB itself. Among the information provided is the name of the HME, theshape of the HME footprint, and the number of system connectors on theDAB.

Certain circuitry of the HME may require periodic stimulation(refreshing) when the HME is not being used by the HMS for a period oftime. Without being refreshed, this circuitry may drift or bepermanently damaged. The DAB preferably includes a keepalive clockingcircuit that connects to the clock pins of the HME to provide clocksignals to the HME circuitry. The keepalive circuitry keeps the HMErefreshed when it is not being accessed by the HMS.

The HMS will commence an evaluation sequence of the HME only after theHME has been initialized. The DAB feedback circuitry connectspredetermined HME outputs to the PEL. When the feedback signal indicatesthat the HME has reached a predetermined state, the evaluation sequencewill commence, if all other evaluative requirements are met.

The DAB analog sense circuitry connects the HME analog outputs to thePEL circuitry. The PEL processes the HME analog outputs for evaluationof certain operations of the HME.

The DAB presence detection circuitry indicates whether a DAB isplugged-in to the PEL, and indicates the DAB's particular location onthe HMS. The DAB status indicators provide visual indications that theDAB is plugged-in and powered-up, and whether it is in use, i.e.,whether the HME is being used by one or more simulations.

The DAB test points are used for synchronizing, for example, theoperation of external test equipment with the operation of the HME. Thetest point signals may be used for marking the occurrence of eventsmarking specific points in time when the HME is being evaluated. The DABpreferably has an area where additional circuitry or components may beconnected to the DAB. The additional circuitry or components may be usedto supplement the operation of different features of the DAB or toprovide supplemental circuitry for the operation of the HME.

An object of the present invention is to provide a DAB for connecting anHME to the PEL of an HMS.

Another object of the present invention is to provide a DAB forconnecting an HME to the PEL of an HMS that will allow the DAB with theattached HME to be connected to the PEL of a powered HME.

A further object of the present invention is to provide a DAB forconnecting an HME to the PEL of an HMS that has memory for identifyingthe HME, DAB, and their characteristics.

A yet further object of the present invention is to provide a DAB forconnecting an HME to the PEL of an HME that provides signals to the PELto indicate that the DAB is present, and to indicate where it isconnected.

A still further object of the present invention is to provide a DAB forconnecting an HME to the PEL of an HMS that provides signals to the PELto indicate when the HME has been initialized.

An object of the present invention is to provide a DAB for connecting anHME to the PEL of an HMS that has an HME connector (i.e., HME footprintand means of HME connection) to which a class or family of HMEs may beconnected.

These and other objects of the invention will be described more fully inthe remainder of the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the DAB of the present invention.

FIG. 2 is schematic drawing of the electrostatic dissipation circuitryof the DAB of the present invention.

FIG. 3 is a schematic drawing of the live insertion circuitry of the DABof the present invention associated with the +5 V supply voltage.

FIG. 4 is a schematic drawing of the live insertion circuitry of the DABof the present invention associated with the +12 V supply voltage.

FIG. 5 is a schematic drawing of the live insertion circuitry of the DABof the present invention associated with the -5.2 V supply voltage.

FIG. 6 is a schematic drawing of the live insertion circuitry of the DABof the present invention associated with the -12 V supply voltage.

FIG. 7 is a schematic drawing of the IMEVCC generation circuitry of theDAB of the present invention.

FIG. 8 shows a representative portion of the HME connector.

FIGS. 9 through 19 show representative HME footprints and footprintconnection methods for accommodating a class or family of pin grid arraypin-out configurations.

FIG. 20 shows a representative HME footprint and footprint connectionmethod for accommodating a class or family of dual in-line packagingpin-out configurations.

FIG. 21 shows a representative HME footprint and footprint connectionmethod for accommodating a class or family of plastic leaded chipcarrier or quad flat-pack pin-out configurations.

FIG. 22 is a schematic drawing of the keep-alive clock circuitry of theDAB of the present invention.

FIG. 23 is a schematic drawing of the memory circuitry of the DAB of thepresent invention.

FIG. 24 is a schematic drawing of the indicator circuitry of the DAB ofthe present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of DAB 100 of the present invention that isused to connect an HME (not shown) to PEL 200 of an HMS.

The DAB is the basic fixture for mounting an HME to the PEL. Systemconnector 102 of the DAB is the structure that mates with PEL 200. Thesystem connector is preferably a 130-pin connector. Eighty pins aresignal pins. Some, but not all, of the remaining 50 pins are forconnecting other signals between the DAB and the PEL.

The connection between DAB 100 and PEL 200 is represented bybi-directional signal connector 102. The pins of system connector 102that mate with the appropriate section of PEL 200 preferably have theassignments shown in Table 1:

                  TABLE 1                                                         ______________________________________                                        Signals    Direction  Description                                             ______________________________________                                        CLK10MHz   From PEL   The two keep-alive                                      CLK1MHz    to DAB     clock signals.                                          EECLK      From PEL   The clock to the DAB                                               to DAB     EEPROM                                                  EEIN       From PEL   The serial input to                                                to DAB     the DAB EEPROM.                                         EEOUT      From DAB   The serial data output                                             to PEL     from the DAB EEPROM.                                    EESEL      From. PEL  The select signal for                                              to DAB     the DAB EEPROM.                                         ESD GND    Common     The ground line that                                                          dissipates electrostatic                                                      charge from the DAB to                                                        the chassis ground of                                                         the HMS. The earliest                                                         mating connection pin                                                         of the system connector                                                       is associated with this                                                       signal.                                                 FEEDBACK   From DAB   Signal to indicate                                                 to PEL     that the HME is                                                               initialized.                                            HME ANALOG From DAB   Analog signal from the                                             to PEL     HME sent to the PEL                                                           for measurement.                                        HME SIG    Bi-direc-  Signals transmitted                                                tional     between the signal                                                 between    pins of the HME and                                                DAB and    the PEL.                                                           PEL                                                                HMEVCC     From DAB   One or more signals                                                to HME and generated in the DAB                                               PEL        that are sent to the                                                          HMS for measurement,                                                          sent to power the HME,                                                        and sent to the PEL to                                                        be used as a reference                                                        and/or driver supply                                                          voltage.                                                INUSELED*  From PEL   Negative-true signal                                               to DAB     from the DAB to the                                                           in-use status LED.                                      KEEPALIVE* From PEL   Negative-true signal                                               to DAB     that enables the keep-                                                        alive clock buffers.                                                          May also be used to                                                           synchronize external                                                          test equipment.                                         PEL M12V   From PEL   The -12 V supply voltage.                                                     to DAB                                                  PEL P12V   From PEL   The +12 V supply voltage.                                                     to DAB                                                  PRESENT*   From DAB   Negative-true signal                                               to PEL     to indicate that the                                                          DAB is connected to                                                           the PEL.                                                SIG GND    Common     Signal ground. At                                                             least one signal                                                              ground connection pin                                                         of the system connector                                                       is associated with an                                                         early-mate pin.                                         USER       From PEL   One or more signals                                                to DAB     from the PEL for output                                                       from the DAB to external                                                      equipment for                                                                 synchronization.                                        +5 PELVCC  From PEL   The +5 V supply voltage.                                                      to DAB                                                  -5.2       From PEL   The -5.2 V supply                                       PELVCC                to DAB voltage.                                         ______________________________________                                    

The "*" designation after a signal or signal name indicates the invertedstate of the signal without the "*" designation, as is known by thoseskilled in the art.

The number of system connectors needed to support a particular HME isdetermined by the number of HME pins. As stated, each system connectorhas 80 signal pins intended for connection to HME pins. Preferably, upto four system connectors may be connected together as part of one DAB.Hence, a DAB may support HMEs that have up to 320 pins. When a DAB hasmore than one system connector, only the first system connectorcommunicates with the PEL with respect to all of the signals indicatedabove. The remaining system connectors communicate only with respect tothe HME SIG signals, the PRESENT* signal, HMEVCC signal, ground lines,and the power supply signals.

The remainder of the components and circuitry of the DAB will now bedescribed.

Referring to FIGS. 1-6, live insertion of the DAB will be described. By"live insertion," it is meant that the DAB, with the attached HME, isconnected to the PEL of a powered HMS.

Live insertion of the DAB involves the use of live insertion circuitry108, the physical structure of system connector 102, and electrostaticcharge dissipation ("ESD") circuitry 120. The combination of thesecircuitries and the structure permit the DAB to be live-inserted.

Live insertion preferably is performed in three phases: (1)electrostatic charge dissipation, (2) signal ground equalization, and(3) gradual power-up of the DAB and HME. The first two involve the ESDcircuitry and the physical structure of the system connector, while thelast is performed by live insertion circuitry 108.

System connector 102 and PEL 200 mate in a male/female relationship,with the system connector being the male fitting. The various pins ofsystem connector 102 mate with the PEL over a period of time such thatthere are three classes of pins. Pins in the first class all mate beforeany pins in the second or third classes mate. Pins in the second classall mate before any pins in the third class mate. During removal(unmating), the order of mating is reversed, that is, pins in the thirdclass unmate first, followed by pins in the second class, followed bypins in the first class. Pins in the first class are associated withelectrostatic charge dissipation, while pins in the second class areassociated with the signal ground equalization, and pins in the thirdclass are associated with the remainder of the above-discussed signalstransmitted between the DAB and PEL.

In the preferred embodiment, there is one pin on the system connector ineach of the first and second classes, and the remaining pins fall intothe third class. The sequence of mating is accomplished by using pins ofthree different lengths. As the DAB and PEL are mated, the longest pinsmate earliest, and the differences between successive pin lengths allowsfor the physical (and therefore time) skew inherent in connector mating.Pins in the first class are 0.50 inches longer than pins in the thirdclass. Pins in the second class are 0.25 inches longer than pins in thethird class. Alternatively, the elongated pins may be part of theconnector on the PEL.

With respect to electrostatic charge dissipation, the surface of the DABcan build up substantial amounts of electrostatic charge prior toconnection to the PEL. This charge must be leaked off before the DABsignal pins mate with the pins of a powered PEL. This electrostaticcharge may reach as much as 15 KV. If it is not leaked off beforegeneral mating takes place, the discharge of the electrostatic charge tothe PEL circuitry may cause considerable damage to the PEL, the HME, andto the HMS in general.

Referring to FIGS. 1 and 2, electrostatic change dissipation will bedescribed. ESD GND line 122 connects to the longest pin of systemconnector 102. The ESD GND line also connects to DAB fascia 256. Assystem connector 102 mates with the female connector of PEL 200, theearliest-mating pin of the system connector connects to chassis groundthrough the fascia of the PEL. When the earliest-mating pin makescontact, the electrostatic charge on the DAB fascia is dissipated to ESDGND line 122, which is the chassis ground of the HMS.

ESD GND line 122 also connects to SIG GND line 254 through resistor 252.This provides a leakage path between SIG GND line 254 and chassisground, therefore preventing any significant voltage potential fromdeveloping on chassis ground with respect to signal ground. Resistor 252is very large. In the preferred embodiment, it is 1M ohm.

After the DAB is mated to the PEL, it must still be able to dissipateelectrostatic charge. This protects the DAB if, for example, an operatortouches the DAB when he or she is carrying electrostatic charge. The DABfascia has a spring connected to it that is biased against sheet metal(chassis ground) of the HMS when the DAB is connected. This arrangementdirectly dissipates electrostatic charge which has been imparted to theDAB fascia to chassis ground.

With respect to signal ground equalization, the signal grounds of theDAB and PEL may not be at the same level before they are mated. Withoutfirst equalizing this potential difference, and maintaining a consistentsignal ground connection between the PEL and DAB through the remainderof the mating process, other power supply voltages could couple throughthe HME or other components to the DAB signal ground, and then throughthe HME or other components to signal lines, sending a damaging voltagelevel to the PEL. Signal ground equalization occurs after electrostaticcharge dissipation, but before the mating of the remainder of the DABsystem connector pins with the PEL.

The early-mating signal ground pin (of the second class of systemconnector pins) fulfills this requirement. When the PEL and DAB mate andelectrostatic charge has been dissipated, SIG GND line 254, which isconnected to the early-mate signal ground pin, contacts the pin on thePEL connector to which signal ground is connected before any of theremaining signals on the DAB system connector mate to the PEL. Once theearly-mate signal ground mates, the PEL and DAB signal grounds areequalized essentially instantaneously.

Following equalization of the signal grounds, the DAB signal pins matewith the female connector of the PEL. When the two mate, the variousvoltage supplies are supplied to the DAB to power the DAB and the HME.Without some type of protection at mating, the bulk capacitance of theDAB and HME circuitry would draw instantaneous current, causing amassive current in-rush to the DAB and HME, and serious voltagedepletions in the PEL and HMS in general. The result of this could beuncontrolled transients in the system, components changing state, anddamage to the HME, PEL, and HMS. To prevent this massive currentin-rush, the DAB ramps-up the supply voltages in a manner that will nowbe described.

The mating skew among all the pins in the third class when the DABsystem connector and female PEL connector mate is approximately 10milliseconds. The live insertion circuitry turns on the power suppliesin a period equal to or greater than this skew. This roughly emulatesthe behavior of the typical DC switching power supply used in electronicsystems, in which multiple supplies turn on and ramp up at approximatelythe same time. As with the typical switching power supply, theparticular sequencing of supply turn-on is not specified or guaranteed.

At mating, the PEL provides four power supply voltages to the DAB. Theseare input to live insertion circuitry 108 via bus 110. The four voltagesare +5 V, -5.2 V, +12 V, and -12 V. The circuitry to ramp-up these powersupplies will now be described.

Referring to FIG. 3, the circuitry to ramp-up the +5 V PELVCC signal online 302 is generally shown at 300. The +5 V PELVCC signal on line 302is input to N-channel MOSFET 304. The gate of the MOSFET is connected toa timing circuit that ramps-up the +5 V PELVCC signal at the output ofthe MOSFET on line 306. The +5 V live insertion circuitry includes the+12 V supply voltage signal PEL P12V on line 330, which is input to line324 of the timing circuit. Diode 318 and timing resistor 314 areconnected in parallel in line 324, and the end of line 324 connects tothe gate of MOSFET 304. Line 310 connects between the gate of MOSFET 304and SIG GND line 254. Timing capacitor 308 is connected in line 310.

Line 332 is connected in parallel with lines 324 and 310 (takentogether) between the +12 V supply voltage and SIG GND line 254.Discharge resistor 334 is disposed in this line. Timing resistor 314 hasa much higher value than discharge resistor 334. This relationshipensures that the time constant of the timing capacitor and dischargeresistor is much less than the time constant of the timing capacitor andthe timing resistor.

As the DAB and PEL are mated, the contacts of the connectors bounce.During bouncing, when the PEL P12V signal on line 330 is connected,timing capacitor 308 charges to +12 V through timing resistor 314. WhenPEL P12V is disconnected, the timing capacitor 308 discharges throughdiode 318 and discharge resistor 334. Over the period of bouncing, thatthe time constant of the discharge circuit is very short compared tothat of the timing circuit, and that the timing circuit time constant iscomparable to the expected length of the bouncing period, ensures thatthe timing capacitor will not fully charge until the connectors arefully mated. When, however, the DAB and PEL have been fully mated on theorder of the time constant of the timing resistor 314 and timingcapacitor 308, and the PEL P12V signal has stabilized, the gate voltageof the MOSFET will approach +12 V. This turns on the MOSFET and ramps-upthe +5 V HMEVCC signal at the output of the MOSFET on line 306. Theramp-up of the +5 V supply voltage takes place in the threshold regionof the MOSFET (i.e., the gate voltage compared to +5 V), and the slopeof the ramp depends on the current demand.

The live insertion circuitry for the +12 V supply voltage is shown inFIG. 4 at 350. The +12 V supply voltage is input to the live insertioncircuitry as the PEL P12V signal on line 330. This signal is input toP-channel MOSFET 370. The gate of MOSFET 370, like the gate of MOSFET304 of the +5 V live insertion circuitry, is connected to a timingcircuit.

The timing circuit uses the supply voltage, not a separate voltage, toinitiate its actions. Line 354 of the timing circuit, with dischargeresistor 355, is connected in parallel with line 56. Line 356 includes atiming capacitor 358 connected in series with the parallel combinationof timing resistor 360 and diode 366. Line 364 connects diode 366 andtiming resistor 360. Line 365 connects line 364 to the gate of MOSFET370. SIG GND line 254 connects to the return side of the timing circuit.The value of the discharge resistor is much less than that of the timingresistor, for the same reason as set forth for the +5 V live insertioncircuitry. That is, the time constant of the discharge resistor and thetiming capacitor is much less than the time constant of the timingresistor and the timing capacitor.

As stated, during mating of system connector 102 and the femaleconnector of the PEL, signal bouncing occurs. During bouncing, timingcapacitor 358 and timing resistor 360 act as a differentiator, bringingthe signal at the gate of the MOSFET up to +12 V or more when PEL P12Vmakes contact. When contact is lost, timing capacitor 358 rapidlydischarges through diode 366 and discharge resistor 355, the gatevoltage returns to the same as PEL P12V, and the MOSFET 370 remainsturned off.

When the DAB and PEL have been fully mated on the order of the timeconstant of timing resistor 360 and timing capacitor 358, the voltage atthe gate of the P-channel MOSFET approaches 0 V. As this takes place,the output of MOSFET 370 on line 372 will ramp-up to +12 V. As stated,the ramp-up of the MOSFET output is over the threshold region (i.e., thegate voltage compared to +12 V), and the slope of the ramp is dependenton the current demand.

The remaining two live insertion circuits are associated with the -5.2 Vand -12 V supply voltages. These circuits are similar to the circuitdisclosed for the +12 V supply voltage, except that their MOSFETs areN-channel rather than P-channel devices. Because of this, the diode isreversed in the -5.2 V and -12 V timing circuits. Since the -5.2 V and-12 V circuits are the same, the -5.2 V circuit shown in FIG. 5 will bedescribed, and the reference numbers of the -12 V circuit (shown in FIG.6) will follow in parenthesis.

Referring to FIG. 5 (FIG. 6), the live insertion circuitry for the -5.2V (-12 V) supply voltage is shown generally at 400 (450). The -5.2 V(-12 V) supply voltage is input to the live insertion circuitry as the-5.2 PELVCC (PEL M12V) signal on line 402 (452). This signal is input tothe source of N-channel MOSFET 412 (462). The gate of the MOSFET, likethe gate of the MOSFET associated with the +5 V live insertioncircuitry, is connected to a timing circuit.

The timing circuit has line 404 (454) with discharge resistor 406 (456)connected in parallel with line 408 (458). Line 408 includes timingcapacitor 410 (460) connected in series with the parallel combination oftiming resistor 420 (470) and diode 418 (468). Line 414 (464) connectsthe diode and timing resistor. Line 415 (465) connects line 414 (464) tothe gate of MOSFET 412 (462). SIG GND signal line 254 connects to thereturn side of the timing circuit. The value of the discharge resistoris much less than that of the timing resistor for the same reason setforth for the previous circuits. That is, the time constant of thedischarge resistor and the timing capacitor is much less than the timeconstant of the timing resistor and the timing capacitor.

During bouncing, timing capacitor 410 (460) and timing resistor 420(470) act as a differentiator, bringing the signal at the gate of theMOSFET down to -5.2 V (-12 V) or less when -5.2 V PELVCC (PEL M12V)makes contact. When contact is lost, timing capacitor 410 (460) rapidlydischarges through diode 418 (468) and discharge resistor 406 (456), thegate voltage returns to the same as -5.2 V PELVCC (PEL M12V), and theMOSFET 412 (462) remains turned off.

When the DAB and PEL have been fully mated on the order of the timeconstant of the timing resistor 420 (470) and timing capacitor 410(460), the voltage at the gate of the N-channel MOSFET 412 (462)approaches 0 V. The ramp-down of the -5.2 V (-12 V) supply voltageoutput on line 416 (466) takes place in the threshhold region of theMOSFET, i.e. the gate voltage compared to -5.2 V (-12 V), and the slopeof the ramp depends on the current demand.

Referring to FIG. 7, the HMEVCC generation circuitry will be described.The HMEVCC generation circuitry is shown generally at 500. Forconvenience, it is assumed that the +5 V HMEVCC signal on line 306 isinput to HMEVCC generation circuitry 500 instead of one of the othersupply voltages. However, it is understood that the input signal couldalso be one of the other supply voltages, -5.2 V, +12 V, or -12 V.

The HMEVCC signal on line 306 connects to lines 502 and 504. Line 502connects to terminal 526 of switch 518. Line 504 connects to the inputof voltage regulator 506. Regulator 506 is commercially available fromLinear Technology, under model number LT1085. The output of voltageregulator 506 is connected to terminal 528 of switch 518.

The output voltage of the regulator is adjusted by the resistor networkconnected to its adjustment input. Line 510, with resistor 512 disposedin it, is connected between the adjustment input and signal ground. Line514, with resistor 516 disposed in it, is connected to line 508 at theoutput of voltage regulator 506. The values of these resistors arechosen to provide an output voltage that will match the voltage requiredfor the HME. Table 2 shows the relationship of the resistors and theregulator output voltages. The RA and RB values correspond to resistors516 and 512, respectively.

                  TABLE 2                                                         ______________________________________                                        VREG      RA Value (ohms)                                                                            RB value (ohms)                                        ______________________________________                                        3.5V      100          180                                                    3.3V       91          150                                                    3.2V       43           68                                                    3.0V       47           68                                                    2.9V       91          120                                                    2.8V      120          150                                                    2.5V       91           91                                                    2.4V      100           91                                                    2.2V      120           91                                                    2.0V       91           56                                                    1.8V       75           33                                                    1.5V      120           27                                                    ______________________________________                                    

Assuming, for descriptive purposes only, that the voltage output on line508 of the voltage regulator is 3.3 V, switch 518 has 3.3 V at terminal528 and 5 v at terminal 526. Depending on the specific HME connected tothe DAB, one of these will be selected for output from the switch online 520 via terminal 530.

Fuse 522 is disposed in line 520 to protect the HME and HMS should therebe a short from HMEVCC to another supply voltage or ground. The signaloutput from the HMEVCC generation circuitry is the HMEVCC that is inputto the HME connector, and is returned to the PEL for use as a referencevoltage and/or driver supply voltage.

The HME connector includes the HME footprint, the HMEVCC connections,and signal ground connections. A representative portion of the HMEconnector for a pin-grid array HME footprint is diagrammed in FIG. 8 at550. In FIG. 8, "X" sites 552 are the HME footprint pads that receivethe pins of the HME, "V" sites 554 are the HMEVCC pads, and "G" sites556 are the signal ground pads. Since the HME "X" sites are arranged on0.1 inch centers, the maximum distance from any "X" site to either a "V"or "G" site is 0.71 inches. Hence, when the pins of the HME areconnected to the "X+ sites, any pins that are signal ground pins orvoltage supply pins can be easily connected to a "G" or "V" site,respectively.

It is understood that the relationship of the "X," "V," and "G" sitesfor the various types of HME packaging will be different, and that theseother relationships are within the scope of the present invention.

FIGS. 9-19 refer to HME footprints and methods of connecting footprintpads. The HME footprint of the present invention will accommodate HMEpin-out configurations of a class or family of HMEs. Four specificclasses or families of HMEs with a variety of pin-out configurationsaccommodated by the HME footprint method of the present invention areHMEs with pin grid array ("PGA") pin-out package configurations, dualin-line ("DIP") pin-out package configurations, plastic leaded chipcarrier ("PLCC") pin-out package configurations, and quad flat-pack("QFP") pin-out package configurations. However, it is understood thatthe method of HME footprint construction and pad connection disclosedherein is equally applicable to other pin-out configuration types. Inthe following, the PGA, the DIP, the PLCC, and then the QFP footprintsof the present invention will be described.

The pins of HMEs with a PGA pin-out configuration are generally arrangedin concentric rectangular rings. The matrix of the connection pads ofthe HME connector are arranged in the same manner. One HME footprintthat supports HMEs with PGA pin-out configurations has a 20-by-20 matrixof connection pads, with 0.1 inch centers in both directions. Each ofthese pads may be connected to a separate pin of system connector 102,however, it is not a requirement that each pad do so. Therefore, thisHME footprint could, at a maximum, support HMEs with up to 400 pins.

In the preferred embodiment, up to four system connectors may be usedwith one DAB, and each system connector has 80 signal pins forconnection to the HME. Hence, the largest DAB would support a 320-pinHME. However, it is understood that system connectors with a greaternumber of signal pins or a greater number of system connectors arewithin the scope of the present invention to support the 400 pad HMEfootprint or even larger HME footprints.

The preferred embodiment of the HME footprint has a 20-by-20 matrix (or400 pads). For purposes of illustration, the HME to be connected to theDAB has 240 pins. Since each system connector has 80 HME signal pins,three system connectors are required to support this HME.

The following is a description of the HME footprint pad connection tosupport a class or family of PGA pin-out configurations having 240 pinsor less.

The following criteria are important to the connection of the pads ofthe matrix: (1) the total number of pads of the footprint can exceed thetotal number of signals from system connector 102; (2) each of the 240data pins of the three system connectors are first routed to one pad ofthe 400 pad footprint; (3) two or more connection pads may be connectedto the same system connector pin, as long as two HME pins (footprintpads) are not connected together when the HME is plugged into thefootprint; and (4) PGA pin-out configurations generally start with thelargest possible complete rectangular range and work inwardly, formingsuccessively smaller concentric rectangular rings, and if the innermostring is not complete, corner and center position of the innermost ringare most commonly selected for the placement of pins.

Following this criteria, connection of an HME footprint to the systemconnectors for a 240 pin HME will be described. FIG. 9, at 600, showsthe initial set of pads to which the 240 pins of the three systemconnectors are connected. "X" sites 602 represent the pads of thefootprint. The pads are individually connected to each of the 240available HME signal lines on the system connectors starting with theoutermost concentric ring, with 20 pads at each side, and working inwarduntil all 240 pads are connected. It is to be noted that the innermostring is partially complete, and as specified, "X" sites 610 at thecorners and the "X" sites at the centers 606 and 608 are connected,rather than other positions. The remainder of the figures, FIGS. 10-19,describe the connections to accommodate fixturing of PGA pin-out HMEswith, at most, 240 pins, and with, at most, a 20-by-20 outermostrectangular ring of pins. In each of the figures, the center at 604includes HME footprint pads which are either unconnected or which may beconnected in a subsequent step of this procedure to system connector HMEsignal lines that have already been assigned.

FIG. 10 at 620 shows how the original 20-by-20 rectangular ring of pinsis treated to produce a new HME footprint with a 19-by-19 rectangularring of pins. Two adjacent sides of the outermost ring, designated by"#" sites 622, represent the 39 HME footprint pads which are notrequired in the 19-by-19 HME footprint. The 39 "0" sites 624 are thoseHME footprint pads which are filled in to the previous 20-by-20 HMEfootprint to form an optimal 19-by-19 240-pin HME footprint. By optimal,it is meant that the criteria for filling concentric rings and thenassigning remaining pins to corner and middle positions are met. The 39"#" sites 622 are pairwise connected with the 39 "0" sites 624. Thus,each "0" site shares one system connector pin with a corresponding "#"site. FIG. 11 shows the resulting 19-by-19 HME footprint.

This process of connecting the footprint pads is followed in thesequence of the HME foot-print arrangements shown in FIGS. 12 to 19, aswill be described.

FIG. 12 at 640 shows how the 19-by-19 HME footprint is treated toproduce a new HME footprint with a 18-by-18 rectangular ring of pins.Two adjacent sides of the outermost ring, designated by "#" sites 642,represent the 37 HME footprint pads which are not required in the18-by-18 HME footprint. The 37 "0" sites 641 are those HME footprintpads which are filled in to form an optimal 18-by-18 240-pin HMEfootprint, where optimal is as previously defined. The 37 "#" sites 642are pairwise connected with the 37 "0" sites 641. Thus, each "0" siteshares one system connector pin with a corresponding "#" site. FIG. 13shows the resulting 18-by-18 HME footprint.

FIG. 14 at 660 shows how the 18-by-18 HME footprint is treated toproduce a new HME footprint with a 17-by-17 rectangular ring of pins.Two adjacent sides of the outermost ring, designated by "#" sites 662,represent the 35 HME footprint pads which are not required in the17-by-17 HME footprint. The 35 "0" sites 664 are those HME footprintpads which are filled in to form an optimal 17-by-17 240-pin HMEfootprint, where optimal is defined as previously. The 35 "0" sites 662are pairwise connected with the 35 "0" sites 664. Thus, each "0" siteshares one system connector pin with a corresponding "#" site. FIG. 15shows the resulting 17-by-17 HME footprint.

FIG. 16 at 680 shows how the 17-by-17 HME footprint is treated toproduce a new HME footprint with a 16-by-16 rectangular ring of pins.Two adjacent sides of the outermost ring, designated by "#" sites 682,represent the 33 HME footprint pads which are not required in the16-by-16 HME footprint. The 33 "0" sites 684 are those HME footprintpads which are filled in to form an optimal 16-by-16 240-pin HMEfootprint, where optimal is as previously defined. The 33 "#" sites 682are pairwise connected with the 33 "0" sites 684. Thus, each "0" siteshares one system connector pin with a corresponding "#" site. FIG. 18shows the resulting 16-by-16 HME footprint.

FIG. 18 at 700 show how the 16-by-16 HME footprint is treated to producea new HME footprint with a 15-by-15 rectangular ring of pins. Twoadjacent sides of the outermost ring, designated by "#" sites 702,represent the 31 HME footprint pads which are not required in the15-by-15 HME footprint. The 16 "0" sites 704 are those HME footprintpads which are filled in to form an optimal 15-by-15 240-pin HMEfootprint, where optimal is as previously defined. Note that, in thiscase, there are more available "#" sites than required "0" sites. Only16 of the "#" sites are then required to connect to the "0" sites andtherefore share the same system connector pins. The remaining 15 "#"sites have no further connections.

The center portion that was present in the previous footprints is nowcompletely connected to system connector 102. FIG. 19 at 720 shows theresulting footprint as it is presented to a 15-by-15 HME. Any HME with aPGA pin-out equal to or smaller than 15-by-15 can be plugged into thisHME footprint.

The result of the application of this method is that any HME whosepin-out configuration is a subset of that shown in FIGS. 9, 11, 13, 15,17, or 19, is properly supported by the DAB whose HME footprint has beenconstructed as just described.

This method of connecting the pads of the HME footprint is alsoapplicable if the DABs has one, two, or four system connectors thataccommodate HMEs with PGAs with up to 80, 160, or 320 pins,respectively, or indeed, with any size of HME footprint andcorresponding system connector pins.

FIG. 20 at 750 shows the HME footprint for HMEs with DIP pin-outarrangements. This footprint has base row 752, and rows 754, 756, 758,and 760 spaced from the base row 0.3, 0.4, 0.6, and 0.9 inches,respectively. The footprint will accommodate DIP pin-out arrangementswith different widths having up to 64 pins.

All of the rows, except the base row, are connected in parallel.Specifically, parallel connections 762 connect rows 754 and 756,parallel connections 764 connect rows 756 and 758, and parallelconnections 766 connect rows 758 and 760. In connecting the systemconnector to the footprint connection pads, 32 pins of the systemconnector connect to the base row and 32 other pins connect to the 32parallel connected columns formed by the rows at 0.3, 0.4, 0.6, and 0.9inches from the base row.

This method of connecting the pads of the HME footprint is alsoapplicable for other sizes and spacings of DIP pin-out arrangements. Theparallel connection method for use with DIP pin-out arrangements alsoapplies to HMEs with plastic leaded chip carrier ("PLCC") pin-outarrangements.

Referring to FIG. 21, the HME footprint diagrammed at 800 supports a 28pin PLCC, and can be extended to support larger or smaller PLCCs in thefollowing manner. "X" sites 802, "1" sites 804, and "#" sites 806 arethe initial footprint pads, and together total 28 footprint connectionpads. To support, for example, a 20 pin PLCC, "#" sites 806 areconnected to "2" sites 808. In a like manner, there can be otherfootprint connection pads connected in parallel for PLCC pin-outarrangements with more than 28 pins and less than 20 pins.

By employing different pad shapes and spacing, but using the generalmethod described above for supporting PLCC HME footprints, HMEs with QFPpin-out arrangements can also be supported. Referring to FIG. 21, theHME footprint diagrammed at 800 supports a 28-pin QFP and can beextended to support larger and smaller QFPs, as similarly described forPLCCs.

Referring to FIG. 1, HME footprint 130 is connected to system connector102 by bi-directional connection lines 134 and 136 which pass throughconfiguration area 132. Connection lines 134 and 136, referred to as"traces", may use internal signal layers in the DAB but come to thesurface at the configuration area.

The purpose of configuration area 132 is to provide an area where linesbetween the HME and the PEL can be altered to prevent problems or toimplement special features. The following are some uses of theconfiguration area, but it is to be understood that there may be otherswhich would be within the scope of the invention.

A first representative situation in which a line would be cut atconfiguration area 132 is when the HME requires a power supply that isoutside the range of the PEL protection circuitry. Such a voltage coulddamage the HMS and PEL circuitry. Therefore, the line connecting to thispower supply pin on the HME is cut and left unconnected at theconfiguration area.

A second representative situation which dictates that the line be cut atconfiguration area 132 is to include additional circuitry or componentsin the line between the HME and the PEL. This could be, for example, theimplementation of a level translator. This implementation may benecessary if either the PEL is driving at a level that is different fromthe input levels of the HME, or the HME is driving at a level that isdifferent from the input levels of the PEL. The additional circuitry orcomponents, such as the level translator, may be positioned in work area158 which will be subsequently described.

A third representative example that requires a line to be cut atconfiguration area 132 is when the load of the line on an analog inputor output of the HME could cause disruption of operation of the HME.

A fourth situation that requires a line to be cut at configuration area132 is to permit the DAB to support previously unconnected HME pins.This may be necessary when the HWE has more pins than HME signal pins inthe system connector. In this case, one of the plurality of linesconnecting to pins on the HME associated with HMEVCC, signal ground, oran unused (no-connect) pints cut, and the system connector side of theline is connected to the previously unconnected pin.

Work area 158, briefly mentioned above, is an area where additionalcircuitry or components may be connected to the DAB. The work area is anarray of pads which are not electrically connected to any supply,ground, or other signals. Alternating HMEVCC and signal ground padspreferably surround the work area for connection to the circuitry orcomponents connected to the work area. Representative examples of thecircuitry or components that may be connected to the work area includespecial feedback logic to decode particular HME states into singlerising or falling edges, level translators to match input and outputlevels of the HME and PEL, analog support circuitry for the HME, andspecial HME clock drivers.

During HMS operation, there are periods when a particular HME is notbeing accessed by the HMS. Some HME components, however, requirerefreshing during such idle periods. If they are not refreshed, thecertain circuitry within the HME may drift, requiring it to warm-up andrestabilize before it can be evaluated again, or resulting in permanentdamage to the HME.

FIG. 22, generally at 850, shows keepalive clock circuitry 154 ofFIG. 1. Referring to FIGS. 1 and 22, system connector 102 receives twokeepalive clock signals and an enable signal from the PEL. The systemconnector provides these signals to the keepalive clock circuitry viaparallel input 156 (FIG. 1). As shown in FIG. 22, the input signals arethe CLK10MHz signal on line 852, the CLK1MHz signal on line 856, and theKEEPALIVE* signal of line 868. The CLK10MHz and CLK1MHz signals areinput to the data inputs to buffer 860. The KEEPALIVE* signal is inputto the negative-true output enable input to the buffer. When theKEEPALIVE* signal has a logic low value, the CLK10MHz and CLK1MHzsignals are output from buffer 860 as the BUF CLK10MHz and BUF CLK1MHzsignals on lines 854 and 858, respectively. The BUF CLK10MHz or BUFCLK1MHz signals can be connected to clock pins of the HME. The PELdrives the KEEPALIVE* signal to a logic low value a predetermined timeafter the end of the last HMS access until the next HMS access.

Referring to FIGS. 1 and 23, the DAB includes electrically-eraseableprogrammable read-only memory (EEPROM) 124. Preferably, EEPROM 124 ismodel NMC9346 manufactured by National Semiconductor. The informationthat may be stored in EEPROM 124 includes the manufacturer of the HME,the device designation of the HME, the manufacturer and revision of theDAB, the revision of the associated software, the number of systemconnectors, the number of supported pins, the type of HME footprint, thetype and size of DAB, and other information useful for the properoperation of the HMS.

EEPROM 124 and the signals associated with it are shown in FIG. 23 at900. The EESEL signal on line 904 is input to the chip select input("CS"), the EECLK signal on line 906 is input to the clock input("CLK"), and the EEIN signal on line 908 is input to the data input("D1") of EEPROM 124. The output of EEPROM 124 is the EEOUT signal online 910. As is appropriate for the usage of this particular EEPROM,when the EESEL signal has a logic high value and the EECLK signal hassuccessive low-to-high transitions, then values on EEIN are shifted inserially to the EEPROM to form access commands, memory addresses, anddata to be stored in memory. Access commands may include read commands,in which case data is shifted out serially from the EEPROM to formsuccessive values on the EEOUT signal, sent to the PEL, and read by theHMS. In general usage, the HMS monitors the EEOUT signal, and directsthe EEIN, EESEL, and EECLK lines to the appropriate sequence of statesas required to write and read the contents of the EEPROM.

It is desirable for the HMS to know when and where a DAB is connected.This is accomplished by presence detection circuitry 104 (FIG. 1). Inthe preferred embodiment, this circuitry includes line 106, connected toSIG GND line 254. Therefore, when the system connector 102 is mated withthe connector of the PEL, the PRESENT* signal with a logic low value isprovided at the appropriate system connector pin. The PEL sensing thisstate of the PRESENT* signal will process it and determine that a DAB ispresent at that location.

It is in the scope of the present invention that other circuitry couldbe used that would provide some other type of signal to indicateconnection of the DAB and its location. Important here, however, is thatthere is a signal generated that is recognizable by the PEL and,therefore, by the HME, which indicates that the DAB is present, andindicates where it is located.

The DAB indicators, shown generally at 140 of FIG. 1, are shown indetail in FIG. 24 at 950. Referring to FIG. 24, the DAB has twoindicators: one indicates that the DAB is connected to the PEL and thatHMEVCC is powering the HME, and the other indicates that the HME on theDAB is being evaluated by the HMS.

With respect to the first indicator, the HMEVCC signal on line 520connects to the anode of light emitting diode ("LED") 954 and SIG GNDline 254 connects to the cathode via line 956, having current-limitingresistor 958. Once the DAB and PEL are connected, and the HMEVCC signalramps-up, LED 954 will light, indicating this condition.

With respect to the second indicator, the HMEVCC signal on line 520connects to the anode of light emitting diode ("LED") 962 and INUSELED*line 146 connects to the cathode via line 964 having current-limitingresistor 966. The INUSELED* signal is from the PEL. When the HMSevaluates the HME, the level of the INUSELED* signal will change to theequivalent of a ground level signal. When the ground level signal isapplied to the circuit, LED 962 will light.

Referring to FIG. 1, the DAB preferably has test points 148 that areconnected to system connector 102 by line 150. The test points are fortransmitting an output from the DAB to external equipment. The testpoints are used to synchronize operation of the external equipment withthe operation of the HMS and HME.

There are two test points. The first is associated with the time periodduring which the HME is evaluated, i.e., from first to last patterns,and the second, the USER signal, is a pulsed signal to markpredetermined events. The first test point is typically the KEEPALIVE*signal. The second test point is used as desired by the softwareassociated with the HME. Two representative events that may be marked bypulses are the beginning and end of the HME evaluation period. However,it is clear that any event can be so marked and provided to an externaldevice to function as a synchronization trigger.

Again referring to FIG. 1, the DAB has feedback connector 144. Thefeedback connector may consist of one or more pads. The feedbackconnector is jumpered to a pin or pins of the HME.

The signals from the HME that are transmitted via the feedback connectorindicate the internal state of the HME. This is necessary because theHME requires that the HME be at a predetermined state before beginningan evaluation. To reach this predetermined state, the HMS will providecertain stimulus to the pins of the HME and monitor the internal stateof the HME through the signals received from feedback connector 144.When the consistent state is achieved, as represented by the feedbacksignals, the HME is considered initialized and restoration of the HME tothe predetermined state can commence.

Once again referring to FIG. 1, analog sense connector 152 is connectedto system connector 102 via line 154. The analog sense connector mayconsist of one or more pads. The analog sense connector is jumpered toan analog output or outputs of the HME. The analog sense connectorprovides the analog outputs of the HME directly the HMS via line 154 andsystem connector 102.

Monitoring the analog output provides information regarding the changesthat occur in the HME during evaluation that would not be revealed ifonly the digital signals were monitored. For example, a principal outputof an HME may take on a multi-valued analog level. This level can bedirectly measured by the HMS when connected to the analog senseconnector, and the measured value used within the overall softwareapplication.

The terms and expressions which are used herein are used as terms ofexpression and not of limitation. And, there is no intention, in the useof such terms and expressions, of excluding the equivalents of thefeatures shown and described, or portions thereof, it being recognizedthat various modifications are possible in the scope of the invention.

We claim:
 1. A system for connecting at least one electronic device orcircuitry to a hardware modeler when the hardware modeler is powered,for evaluating the performance of the electronic device or circuitry inresponse to stimuli provided by the modeler, comprising:connector means,for connection with the electronic device or circuitry, having at leastone segment for mating with a section of the hardware modeler when thehardware modeler is powered, such that electrical signals can bebi-directionally transmitted between the connector means and themodeler; and insertion circuit means, connected to the connector means,and having at least one electrical signal output, said insertion circuitmeans including electrostatic charge dissipation circuitry connected tothe connector means configured to effect first contact with the matingsection of the hardware modeler during mating to dissipate electrostaticcharge on the system, ground equalization circuitry connected to theconnector means configured to effect second contact with the matingsection of the modeler to equalize ground levels of the system and thehardware modeler, and power supply control circuitry connected to theconnector means configured to effect third contact with the matingsection of the modeler to allow ramp-up of a power supply voltage inputto the system based on a predetermined time constant said insertioncircuit means and said connector means allowing for the connection anduse of more than one electronic device or circuitry with a poweredhardware modeler at any given time.
 2. The system as recited in claim 1,wherein the connector means further comprises a multi-pin electricalconnector with first, second, and third segments.
 3. The system asrecited in claim 2 wherein, the first segment comprises at least one pinthat is longer than the pins of the second and third segments and thesecond segment comprises at least one pin that is longer than at leastone pin that comprises the third segment.
 4. The system as recited inclaim 1, wherein the power supply control circuitry includes circuitrythat will ramp-up a power supply voltage input to the system based on apredetermined time constant.
 5. The system as recited in claim 4,wherein the time constant is greater than 1 ms.
 6. The system as recitedin claim 1 wherein the power supply control circuitry includes circuitrythat will ramp-up the current input to the system based on apredetermined time constant.
 7. The system as recited in claim 6,wherein the time constant is greater than 1 ms.
 8. The system as recitedin claim 1, wherein the system further comprises means to refresh theelectronic device or circuitry when the electronic device or circuitryis unaccessed for a predetermined period of time.
 9. The system asrecited in claim 1, wherein the system includes circuitry to providepredetermined electrical signals to the hardware modeler when the systemis connected to the hardware modeler.
 10. The system as recited in claim1, wherein the system includes indicator means to indicate when thesystem is powered by the hardware modeler.
 11. The system as recited inclaim 10, wherein the indicator means includes a light-emitting diode.12. The system as recited in claim 11 wherein, the indicator meansincludes a light-emitting diode.
 13. The system as recited in claim 1,wherein the system includes indicator means to indicate when thehardware modeler accesses the electronic device or circuitry connectedto the system.
 14. The system as recited in claim 1, wherein the systemhas means for providing electrical signals representative of theinternal state of the electronic device or circuitry to determine whensuch electronic device or circuitry is initialized.
 15. The system asrecited in claim 1, wherein the system includes means for providingoutput electrical signals synchronizing the operation of an externaldevice with the operation of the electronic device or circuitry.
 16. Thesystem as recited in claim 1, wherein the system includes circuitreconfiguration means for reconfiguring predetermined circuitry of thesystem.
 17. The system as recited in claim 16, wherein the circuitreconfiguration means comprises an area of the system that includeslines carrying electrical signals between the hardware modeler andelectrical devices or circuitry coming to the surface of a systemsubstrate.
 18. The system as recited in claim 1, wherein the systemincludes means for providing analog electrical signals from theelectronic device or circuitry to verify proper operation of theelectronic device or circuitry.
 19. A method of connecting electricalconnection sites of a electronic device or circuitry connection matrixof a system that is used for connecting the electronic device orcircuitry to a powered hardware modeler that is capable of evaluatingthe performance of the electronic device or circuitry in response tostimuli provided by the modeler, comprising the steps of:(a) determiningfor a class of electronic devices or circuitry a connector pattern of aelectronic device or circuitry with a largest outside connector patterndimension of the class and matrix positions that correspond to aconnector pattern of the electronic device or circuitry with the largestoutside connector pattern dimension of the class; (b) connecting each ofthe matrix position that corresponds to the connector pattern of theelectronic device or circuitry with the largest outside connectorpattern dimension of the class to signal pins of a system connector; (c)determining for the class of electronic devices or circuitry theconnector pattern of the electronic device or circuitry that has thenext largest outside connector pattern dimension and matrix positionsthat correspond to next largest outside connector pattern dimension ofthe class; (d) comparing an inside connector pattern dimension of theelectronic device or circuitry with the next largest outside connectorpattern dimension with an inside connector pattern dimension of theelectronic device or circuitry with the prior largest outside connectorpattern dimension; (e) connecting matrix positions at the insideconnector pattern dimension of the electronic device or circuitry withthe next largest outside connector pattern dimension that are notcorresponding to the matrix positions of the connector pattern of theelectronic device or circuitry with the prior largest outside connectorpattern dimension to the matrix positions previously used by theconnector pattern of the electronic device or circuitry with the priorlargest outside connector pattern dimension that are outside the largestoutside connector pattern dimension of the electronic device orcircuitry of the class with the next largest outside connector patterndimension; and (f) repeating steps (c), (d), and (e) until all of matrixpositions bounded by the matrix positions at the outside connectorpattern dimension of the connector pattern of the electronic device orcircuitry with the largest outside connector pattern dimension.